void main() {
  Map catagory = {'id': 1, 'name': '手机', 'price': '9999'};
  print(catagory['name']);
  print(catagory.keys);
  catagory['品牌'] = '华为';
  print(catagory);
  catagory.remove('id');
  print(catagory);
  catagory.forEach((key, value) {
    print('key:$key,value:$value');
  });
}
